1. Field of the Invention
An aspect of the present invention relates to a photodetector, and more particularly, to a photodetector of an optical pick-up for detecting a reflected light component from an optical disk. The optical pick-up includes a two-wavelength laser diode (LD) radiating a laser beam varying in accordance with the type of optical disk, and the photodetector which converts the detected laser beam into an electrical signal.
An aspect of the present invention relates to a twelve-division photodetector of an optical pick-up for detecting the laser beam radiated by the two-wavelength laser diode that varies with the type of an optical disk and converts the laser beam into an electrical signal.
2. Description of the Related Art
An optical recording and reproducing apparatus records data in an optical disk and reproduces the recorded data into a signal that can be recognized by a user. An optical pick-up is required for recording and reproducing data. When data is recorded, the optical pick-up radiates a laser beam on the surface of an optical disk to form a pit. Also, when the recorded data is reproduced, the optical pick-up optically reads information on the pit formed on the optical disk to output an electrical signal. In order to perform such an operation, the optical pick-up is composed of a plurality of optical elements such as a laser diode (LD) for radiating a laser beam, a diffraction grating, a beam splitter for controlling the deflection of a laser beam, a plurality of lenses for forming an optical path, and a sensor for detecting a signal.
On the other hand, the optical disk used for recording and reproducing data can be of various types. Examples of such disks include, compact disks (CD's) and digital video disks (DVD's). Therefore, recently, an optical recording and reproducing apparatus having a function of recording data in and/or reproducing data from a CD and a DVD is commonly used. In order to record data in and/or reproduce data from such an optical recording and reproducing device, a laser beam having a wavelength that varies with either the CD or the DVD, is radiated. In order to perform such an operation, a conventional optical recording and reproducing apparatus separately includes a CD LD and a DVD LD and, accordingly, a CD optical portion and a DVD optical portion.
The above-described conventional optical pick-up includes two LDs having a complicated structure in an optical system. That is, the number of optical elements that constitute the optical pick-up increases such that the structure of an optical system is complicated. In particular, according to the conventional optical pick-up, when optical elements such as a beam splitter and a photo diode, having an optical path common to the two LDs, are assembled in order to conform the optical axes of the laser beams radiated by two LDs to coincide with each other, a complicated assembling process must be performed. Therefore, according to the conventional optical pick-up, due to the complicated assembling process, productivity is reduced, process yield deteriorates, and the number of optical elements increases thus increasing manufacturing cost.